I have made cels before, and it's fun and easy, 
all it takes is focus. it also goes a lot quicker 
as you practice. however, to respond to your 
point, I don't personally think it's that neat to 
have fancels made of my sketches without having 
requested it myself. unless it's a CG show where 
there are no cels in existence at all. I'm a firm 
believer in the idea of saving up my money until 
the real thing shows up for sale, but that's my 
own opinion(and a few others I'm sure).

/Mina